I am Khedron the Jester. My companion is Alvin.»

«And your business?»

«Sheer curiosity.»

Rather to Alvin’s surprise, the door opened at once. In his experience, if one gave facetious replies to machines it always led to confusion and one had to go back to the beginning. The machine that had interrogated Khedron must have been a very sophisticated one-far up in the hierarchy of the Central Computer.

They met no more barriers but Alvin suspected that they had passed many tests of which he had no knowledge. A short corridor brought them out abruptly into a huge circular cham-ber with a sunken floor, and set in that floor was something so astonishing that for a moment Alvin was overwhelmed with wonder. He was looking down upon the entire city of Diaspar, spread out before him with its tallest buildings barely reaching to his shoulder.

He spent so long picking out familiar places and observing unexpected vistas that it was some time before he paid any notice to the rest of the chamber. Its walls were covered with a microscopically detailed pattern of black and white squares; the pattern itself was completely irregular, and when he moved his eyes quickly he got the impression hat it was flickering swiftly, though it never changed. At frequent intervals around the chamber were manually controlled machines of some type, each complete with a vision screen and a seat for the operator.

Khedron let Alvin look his fill. Then he pointed to the diminutive city and said: «Do you know what that is?»

A1vin was tempted to answer, «A model, I suppose,» but that answer was so obvious that be was sure it must be wrong. So be shook his head and waited for Khedron to answer his own question.

«You remember,» said the Jester, «that I once told you how the city was maintained-how he Memory Banks hold its pattern frozen forever. Those Banks are all around us, with all their immeasurable store of information completely defining the city as it is today. Every atom of Diaspar is somehow keyed, by forces we have forgotten, to the matrices buried in these walls.»

He waved toward the perfect, infinitely detailed simulacrum of Diaspar that lay below them.

«That is no model; it does not really exist. It is merely the projected image of the pattern held in the Memory Banks, and therefore it is absolutely identical with the city itself.

These viewing machines here enable one to magnify any desired portion, to look at it life size or larger. They are used when it is necessary to make alterations in the design, though it is a very long time since that was done. If you want to know what Diaspar is like, this is the place to come. You can learn more here in a few days than you would in a lifetime of actual exploring.»

«It’s wonderful,» said Alvin. «How many people know that it exists?’

«Oh, a good many, but it seldom concerns them. The Council comes down here from time to time; no alterations to the city can be made unless they are all here. And not even then, if the Central Computer doesn’t approve of the proposed change. I doubt if this room is visited more than two or three times a year.»

Alvin wanted to know how Khedron had access to it, and then remembered that many of his more elaborate jests must have involved a knowledge of the city’s inner mechanisms that could have come only from very profound study. It must be one of the Jester’s privileges to go anywhere and learn anything; he could have no better guide to the secrets of Diaspar.

What you are looking for may not exist,» said Khedron, «but if it does, this is where you will find it. Let me show You how to operate the monitors.»

For the next hour Alvin sat before one of the vision screens, learning to use the controls. He could select at will any point in the city, and examine it with any degree of magnification. Streets and towers and walls and moving ways flashed across the screen as he changed the co-ordinates; it was as though he was an all-seeing, disembodied spirit that could move effortlessly over the whole of Diaspar, unhindered by any physical obstructions.

Yet it was not, in reality, Diaspar that he was examining. yet moving through the memory cells looking at the dream image of the city-the dream that had had the power to hold the real Diaspar untouched by time for a billion years. He could see only that part of the city which was permanent; the people who walked its streets were no part of this frozen image. For his purpose, that did not matter. His concern now was purely with the creation of stone and metal in which he was imprisoned, and not those who shared-however willingly -his confinement.

He searched for and presently found the Tower of Loranne, and moved swiftly through the corridors and passageways which he had already explored in reality. As the image of the stone grille expanded before his eyes, he could almost feel the cold wind that had blown ceaselessly through it for per-haps half the entire history of mankind, and that was blowing now. He came up to the grille, looked out-and saw nothing. For a moment the shock was so great that he almost doubted his own memory; had his vision of the desert been nothing more than a dream?

Then he remembered the truth. The desert was no part of Diaspar, and therefore no image of it existed in the phantom world he was exploring. Anything might lie beyond that grille in reality; this monitor screen could never show it.

Yet it could show him something that no living man had ever seen. Alvin advanced his viewpoint through the grille, out into the nothingness beyond the city. He turned the control which altered the direction of vision, so that he looked back-ward along the way that he had come. And there behind him lay Diaspar-seen from the outside.

To the computers, the memory circuits, and all the multitudinous mechanisms that created the image at which Alvin was looking, it was merely a simple problem of perspective. They «knew» the form of the city; therefore they could show it as it would appear from the outside. Yet even though he could appreciate how the trick was done, the effect on Alvin was overwhelming. In spirit, if not in reality, he had escaped from the city. He appeared to be hanging in space, a few feet away from the sheer wall of the Tower of Loranne. For a moment he stared at the smooth gray surface before his eyes; then he touched the control and let his viewpoint drop toward the ground.

Now that he knew the possibilities of this wonderful instru-ment, his plan of action was clear. There was no need to spend months and years exploring Diaspar from the inside, room by room and corridor by corridor. From this new van-tage point he could wing his way along the outside of the city, and could see at once any openings that might lead to the desert and the world beyond.

The sense of victory, of achievement, made him feel light-headed and anxious to share his joy. He turned to Khedron, wishing to thank the Jester for having made this possible. But Khedron was gone, and it took only a moments thought to realize why.

Alvin was perhaps the only man in Diaspar who could look unaffected upon the images that were now drifting across the screen. Khedron could help him in his search, but even the Jester shared the strange terror of the Universe which had pinned mankind for so long inside its little world. He had left Alvin to continue his quest alone.

The sense of loneliness, which for a little while had lifted from Alvin’s soul, pressed down upon him once more. But this was no time for melancholy; there was too much to do. He turned back to the monitor screen, set the image of the city wall drifting slowly across it, and began his search.

Diaspar saw little of Alvin for the next few weeks, though only a few people noticed his absence. Jeserac, when he discovered that his erstwhile pupil was spending all his time at Council Hall instead of prowling around the frontier of the city, felt slightly relieved, imagining that Alvin could come to no trouble there. Eriston and Etania called his room once or twice, found that he was out and thought nothing of it. Alystra was a little more persistent. For her own peace of mind, it was a pity that she had become infatuated with Alvin, when there were so many more suitable choices. Alystra had never had any difficulty in find-ing partners, but by comparison with Alvin all the other men she knew were nonentities, cast from the same featureless mold. She would not lose him without a struggle: his aloofness and indifference set a challenge which she could not resist.